In manufacturing electronic devices, it may be necessary to process a substrate having a non-planar surface. Examples of such devices include three dimensional (3D) FinFETs having raised fins with horizontally and vertically oriented surfaces, and CMOS image sensors (CIS) and eDRAMs, each of which have trenches with horizontally and vertically oriented surfaces. One of the techniques used to process such substrates may include doping to modify electrical, mechanical, optical, and thermal properties, or a combination of such properties of the original substrate. The source/drain (SD) regions of FinFETs, sidewall of shallow trenches in CMOS image sensors, and sidewall of deep trenches (DT) in eDRAMs may be doped to modify the properties of the substrates.
As the electronic devices require uniform properties, it may be desirable for the techniques to conformally process surfaces oriented in different angles. In the doping techniques, for example, it may be desirable to achieve an equal or substantially equal dopant concentration in the regions near the differently oriented surfaces. Although numerous techniques have been proposed, the proposed techniques have achieved limited success. For example, the dopant concentration along the horizontally extending surfaces may be much greater than that of the vertically extending surfaces in these proposed techniques. Such a variation in processing may result in substrates with non-uniform properties, and the final devices may not operate optimally. In addition, some of these processes also deposit material on the substrate, whereby more of the deposited material is disposed on the horizontally extending surfaces than on the vertically extending surfaces. Accordingly, a new technique is needed.